Shahin Nazarian

Bio: Shahin Nazarian is an academic researcher from University of Southern California. The author has contributed to research in topics: Logic gate & Smart grid. The author has an hindex of 18, co-authored 121 publications receiving 1420 citations. Previous affiliations of Shahin Nazarian include Magma Design Automation.

Accurate Timing and Noise Analysis of Combinational and Sequential Logic Cells Using Current Source Modeling

Abstract: A current source model (CSM) for CMOS logic cells is presented, which can be used for accurate noise and delay analysis in CMOS VLSI circuits CS modeling is broadly considered as the method of choice for modern static timing and noise analysis tools Unfortunately, the existing CSMs are only applicable to combinational logic cells In addition to multistage logic nature of the sequential cells, the main difficulty in developing a CSM for these cells is the presence of feedback loops This paper begins by presenting a highly accurate CSM for combinational logic cells, followed by models for common sequential cells, including latches and master slave flip-flops The proposed model addresses these problems by characterizing the cell with suitable nonlinear CSs and capacitive components Given the input and clock voltage waveforms of arbitrary shapes, our new model can accurately compute the output voltage waveform of the sequential cell Experimental results demonstrate close-to-SPICE waveforms with three orders of magnitude speedup

Fast and energy-aware resource provisioning and task scheduling for cloud systems

Abstract: Cloud computing has become an attractive computing paradigm in recent years to offer on demand computing resources for users worldwide. Through Virtual Machine (VM) technologies, the cloud service providers (CSPs) can provide users the infrastructure, platform, and software with a quite low cost. With the drastically growing number of data centers, the energy efficiency has drawn a global attention as CSPs are faced with the high energy cost of data centers. Many previous works have contributed to improving the energy efficiency in data centers. However, the computational complexity may lead to unacceptable run time. In this paper, we propose a fast and energy-aware resource provisioning and task scheduling algorithm to achieve low energy cost with reduced computational complexity for CSPs. In our iterative algorithm, we divide the provisioning and scheduling to multiple steps which can effectively reduce the complexity and minimize the run time while achieving a reasonable energy cost. Experimental results demonstrate that compared to the baseline algorithm, the proposed algorithm can achieve up to 79.94% runtime improvement with an acceptable energy cost increase.

Accelerating Coverage Directed Test Generation for Functional Verification: A Neural Network-based Framework

Abstract: With increasing design complexity, the correlation between test transactions and functional properties becomes non-intuitive, hence impacting the reliability of test generation. This paper presents a modified coverage directed test generation based on an Artificial Neural Network (ANN). The ANN extracts features of test transactions and only those which are learned to be critical, will be sent to the design under verification. Furthermore, the priority of coverage groups is dynamically learned based on the previous test iterations. With ANN-based screening, low-coverage or redundant assertions will be filtered out, which helps accelerate the verification process. This allows our framework to learn from the results of the previous vectors and use that knowledge to select the following test vectors. Our experimental results confirm that our learning-based framework can improve the speed of existing function verification techniques by 24.5x and also also deliver assertion coverage improvement, ranging from 4.3x to 28.9x, compared to traditional coverage directed test generation, implemented in UVM.

Optimal control of PEVs for energy cost minimization and frequency regulation in the smart grid accounting for battery state-of-health degradation

Abstract: Plug-in electric vehicles (PEVs) are considered the key to reducing the fossil fuel consumption and an important part of the smart grid. The plug-in electric vehicle-to-grid (V2G) technology in the smart grid infrastructure enables energy flow from PEV batteries to the power grid so that the grid stability is enhanced and the peak power demand is shaped. PEV owners will also benefit from V2G technology as they will be able to reduce energy cost through proper PEV charging and discharging scheduling. Moreover, power regulation service (RS) reserves have been playing an increasingly important role in modern power markets. It has been shown that by providing RS reserves, the power grid achieves a better match between energy supply and demand in presence of volatile and intermittent renewable energy generation. This paper addresses the problem of PEV charging under dynamic energy pricing, properly taking into account the degradation of battery state-of-health (SoH) during V2G operations as well as RS provisioning. An overall optimization throughout the whole parking period is proposed for the PEV and an adaptive control framework is presented to dynamically update the optimal charging/discharging decision at each time slot to mitigate the effect of RS tracking error. Experimental results show that the proposed optimal PEV charging algorithm minimizes the combination of electricity cost and battery aging cost in the RS provisioning power market.

Negotiation-based task scheduling and storage control algorithm to minimize user's electric bills under dynamic prices

Abstract: Dynamic energy pricing is a promising technique in the Smart Grid to alleviate the mismatch between electricity generation and consumption. Energy consumers are incentivized to shape their power demands, or more specifically, schedule their electricity-consuming applications (tasks) more prudently to minimize their electric bills. This has become a particularly interesting problem with the availability of residential photovoltaic (PV) power generation facilities and controllable energy storage systems. This paper addresses the problem of joint task scheduling and energy storage control for energy consumers with PV and energy storage facilities, in order to minimize the electricity bill. A general type of dynamic pricing scenario is assumed where the energy price is both time-of-use and power-dependent, and various energy loss components are considered including power dissipation in the power conversion circuitries as well as the rate capacity effect in the storage system. A negotiation-based iterative approach has been proposed for joint residential task scheduling and energy storage control that is inspired by the state-of-the-art Field-Programmable Gate Array (FPGA) routing algorithms. In each iteration, it rips-up and re-schedules all tasks under a fixed storage control scheme, and then derives a new charging/discharging scheme for the energy storage based on the latest task scheduling. The concept of congestion is introduced to dynamically adjust the schedule of each task based on the historical results as well as the current scheduling status, and a near-optimal storage control algorithm is effectively implemented by solving convex optimization problem(s) with polynomial time complexity. Experimental results demonstrate the proposed algorithm achieves up to 64.22% in the total energy cost reduction compared with the baseline methods.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Nanoscale thermal transport. II. 2003–2012

Abstract: A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ∼1 nm, the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interface...

A Survey on Demand Response Programs in Smart Grids: Pricing Methods and Optimization Algorithms

Abstract: The smart grid concept continues to evolve and various methods have been developed to enhance the energy efficiency of the electricity infrastructure. Demand Response (DR) is considered as the most cost-effective and reliable solution for the smoothing of the demand curve, when the system is under stress. DR refers to a procedure that is applied to motivate changes in the customers' power consumption habits, in response to incentives regarding the electricity prices. In this paper, we provide a comprehensive review of various DR schemes and programs, based on the motivations offered to the consumers to participate in the program. We classify the proposed DR schemes according to their control mechanism, to the motivations offered to reduce the power consumption and to the DR decision variable. We also present various optimization models for the optimal control of the DR strategies that have been proposed so far. These models are also categorized, based on the target of the optimization procedure. The key aspects that should be considered in the optimization problem are the system's constraints and the computational complexity of the applied optimization algorithm.